>>1025483>a straight line passing from side to side through the centre of a body or figure, especially a circle or sphere.So... from one edge to the other... I measured it at 3cm exactly... are you sure? I mean the measurement I got and the measurement printed on the seat post just don't seem to correlate is all. And this just sorta blew my mind when I did this one... I'm honestly too stupid to own a bike I'm starting to think. Maybe a case of too many cooks in the kitchen? But a bike is my only transport so I really need help with this where I can only hurt myself and not others in a car. Besides I can't afford a license :(